Joseph c



(No Model.)

J. O. EIGHME'YER, TELEPHONE TRANS MITTE'R.

Patented DedQlO, 1889.

n. Prsns. Phokoiilbogmplmr. Wnhington. n c.

" UNITED STATES PATENT." Oriucn.

JOSEPH (J. EICHMEYER, OF UTICA, NEW YORK, ASSIGNOR OF NINE 'IEN'lI-IS TOFRANK J. CALLANEN, JOSEPH R. SYVAN, AND AUGUSTUS ll. PALMER,

ALL OF SAME PLACE.

TELEPHONE-TRANSMITTER.

SPECIFICATION forming part of Letters Patent No. 417,009, dated December10, 1889.

Application filed March 26, 1886. Renewed November 22, 1886. Againrenewed July 27, 1887. Serial No. 245, modem T aZZ whom it may concern:

Be it known that I, JOSEPH. C. EICHMEYER, of Utica, in the county ofOneida and State of New York, have invented certain new and usefulImprovements in Telephone -Transmitters; and I do hereby declare thefollowing to be a full, clear, and exact description of the same,reference being had to the accompanying drawings, forming a part of thisIO specification, and to the letters of reference marked thereon.

My invention relates to improvements in that class oftelephone-transmitters in which the variations in the resistance of thecircuit I 5 are produced by varying the pressure upon 'andcontact-between fine particles of carbon placed in a suitable receptacleby vibrations communicated to them through the medium of a suitablediaphragm or other medium vibrated in accordance with sound waves;

and it consists in a certain improved construction, which I will nowproceed to'describe.

In the drawings, Figure 1 is a longitudinal sectional View of atransmitter constructed in accordance with my invention. Fig. 2 is a topplan view of the same with the top of the casing removed. Fig. 3 is aview of a detail.

A represents the back piece or back, to which the box or chambercontaining the operating parts of the instrument is fastened, adapted tobe secured to the wall or other convenient support; and B represents thebottom board of the receptacle, secured to the back A, as shown, andhaving nearits center a large circular opening.

0 represents a plate, preferably of metal, adapted to be secured to theunder side of the board B by means of a number of screws a, projectingdownward through said board and plate and having nuts I) mounted ontheir lower ends for drawing the plate 0 up against the under side ofboard B. Near the center of the upper side of this plate, and preferablyformed integral therewith, is a circular flange or ring D, closelyfitting the opening in the board and extending up through about flushwith its upper surface. On the inside of this ring is a slight annularshoulder or offset (Z, on which the diaphragm rest-s. The plate 0 isfurther provided near its center with an annular perforation 0, aroundwhich is secured the smaller end of the trumpet-shaped mouthpiece F,flaring outwardly, with the opening toward the front of the instrument.

G represents a conical button or plug, preferably of hard rubber,(though any other similar material will answer,) secured in the smallerend of the trumpet F with its point toward the opening and its upperside fiush with the inside of the plate 0, and provided on its peripherywith aseries of small grooves ff, all as shown in Fig. 3.

II is the diaphragm, consisting, preferably, of a sheet of hard carbonresting upon the annular shoulder of the ring D over the opening in theplate 0, and adapted to be held down in place by means of aring-follower H, of hard rubber or similar non-conducting material,fitting within the ring D and resting upon it. The upper end of thisring H is beveled toward the center, as shown, and upon the upper sideof the ring D are three or more tapped lugs or proj ections e,in whichare mounted pointed screws 6, the ends of the latter being in engagementwith the incline or bevel on the ring 11, so that as they are screwedinthey'will ride up the incline and press the ring and diaphragm firmlydown in position.

Upon the upper side of the board 13 is secured a large metal plate I,having the circular opening, as shown, for accommodation of the rings Dand H, and upon this plate at equal distances apart are secured in anysuitable manner three supports or posts J, constructed preferably ofmetal, though any other material may be employed, if desired, havingtheir upper ends bifurcated, and carbon pencils K are pivoted betweenthe arms thus formed upon pins 7e, passed transversely through them, thepins It being free to move in their bearings in the arms. The longer endof each of the carbon rods or pencils extends down to near the center ofthe diaphragm, the endsbein g preferablymade poly onal, as shown, and,if desired, the faces thus I ble fastenin gs to the board B.

formed smoothed or polished. -A thin layer of. powdered carbon beingplaced upon the diaphragm, the ends of the carbon pencils are broughtdown and the remainder of the cup formed by the ring H and the diaphragmfilled nearly to the top with powdered carbon, as shown in Fig. 1, sothat the ends of the pencils will be embedded in it.

The posts J, that bear the carbon pencils, may be of metal and inelectrical contact with the plate I, or of any other material, and, ifnon-conductors, connection may be made between the plate and pencils bymeans of a wire, or abetter connection may be made between the penciland post by a wire ,2, as shown. The plateI is secured by any suita- Asmall screw m passes down through the board 13 and into the plate C, anda wire 00, connected to this screw at its upper end, forms theconnection between the diaphragm and the battery. The connection betweenthe plate I, on which the pencils are mounted, and the primary of theinduction-coil is formed by the wire 1 as shown.

The operation of the instrument from the above description will now beapparent. The sound entering the trumpet F will pass upward and willsplit, so to speak, upon the end of the button G and pass through thecorrugations on the periphery and be delivered into the chamber belowthe diaphragm and evenly distributed upon the surface of the latter inthe form of a circle, thereby rendering it less liable to be convulsedby harsh or loud discordant sounds. By't'he vibrations of the diaphragmcaused by the 'speakers voice the contact between the pulverized carbonon the diaphragm and the carbon sticks and the resistance of the circuitwill be correspondingly varied, and the impulses transmitted over theline in the ordinary manner through the induction-coil andground-connection.

It will be observed that the contact between the electrodes in myimproved instrument is preserved at all times by an even and regularpressure caused by the weight of the carbon sticks, and by thevibrations of the diaphragm the pulverized carbon will be fed downbetween the pencils, which action, combined with the weight of carbons,will determine the ultimate position of the latter with respect to thediaphragm, and therefore the instrument will not be readily thrown outof adjustment, but is ready at all times to transmit the loudest orfaintest sounds wit-h accuracy.

The faces of the pencils may be smooth and polished, if desired, so asto render the contact better.

It is obvious that various modifications can be devised withoutdeparting from the spirit of my invention, and therefore I do not desireto be limited to the exact construction shown and described herein. Forinstance, a metal diaphragm might be employed having its upper surfacecoated with carbon or even without the coating, or instead of the sticksof carbon metal rods might be used,

the main object being to provide a trans-- mitt-ing-instrument in whichthe contact between the electrodes, one of which is pulverized carbon orequivalent substance, is secured by means of gravity alone.

I claim as my invention.

1. In a telephone-transmitter, the combination, with the diaphragm andthe-mass of finely divided semi conducting material mountedthereon,forming one terminal of an electric circuit, of one or moregravitating electrodes forming the other terminal, pivoted at theirupper ends, and having their lower ends embedded in said semi-conductingmaterial, being held in contact therewith by gravity alone,substantially as described.

2. In a telephone-transmitter, the combination, with the carbondiaphragm and the pulverized carbon thereon, forming one terminal of anelectric circuit, of the pivoted gravitating carbon pencils having oneend embedded in said pulverized carbon forming the other terminal of thecircuit, substantially as described.

3. The combination, with the plate, the ring having the lugs and screwsmounted thereon, the diaphragm, and the ring-follower having the beveledupper side, substantially as described.

4. The combination, with the plate, the ring having the lugs and pivotedscrews therein, and the offset d, forming a seat for the diaphragm, andthe diaphragm, of the ringfollower mounted on the diaphragm, having thebeveled upper side with which the screws co-operate to clamp the lattersecurely in position, substantially as described.

JOSEPH C. EICHMEYER.

Witnesses:

J. G. GIBSON, JAMES W. WATTs.

